Listen to Robert Emmerich introduce The Big Apple, a hit song from 1937. Music written by Bob and performed by Tommy Dorsey's Clambake Seven with Bob on piano. Lyrics written by Buddy Bernier and sung by Edythe Wright. Audio provided by Dorothy Emmerich.

"Soak the rich” means to take money from the rich (such as from taxes) so that the rich people will feel “soaked” (slang for “overcharged” or “ripped off"). “Soak the rich” was much-discussed during the Great Depression and the Revenue Act of 1935 was dubbed a “soak the rich” tax.

The term “soak the rich” has been cited in print since at least October 1921, when Republican Senator George H. Moses of New Hampshire said that a federal tax bill “has been plainly drawn under the inspiration of the inspiring slogan ‘soak the rich.’”

DaveManuel.comDefinition of Soak the Rich
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So what do “soak the rich” and “soak the rich economics” mean exactly?

When you “soak the rich”, you are looking to extract more money from “rich” people in the form of taxes and fees.

Wikipedia: Revenue Act of 1935
The Revenue Act of 1935, 49 Stat. 1014 (Aug. 30, 1935), raised United States taxes on higher income levels, corporations, and gifts and estates.

It was signed into law by President Franklin D. Roosevelt as part of the Second New Deal.

The 1935 Act was popularly known at the time as the “Soak the Rich” tax. It raised tax rates on incomes above $50,000. The Act did little to increase federal tax revenue, and it did not significantly redistribute income. Nonetheless, the bill was very popular and many believed it was a radical departure from tradition. Business leaders and the wealthy were upset about this and other of Roosevelt’s policies and called him a traitor against his own class.

(Oxford English Dictionary)
soak, v.
slang (orig. U.S.). To impose upon (a person, etc.) by an extortionate charge or price; to charge or tax heavily; to borrow or extort money from; to cost a high price. Freq. const. for or with indirect object expressing a sum of money. Hence soak-the-rich phr. attrib. applied to a policy of progressive taxation (progressive adj. 2d); also in similar phrases, as soak-the-poor, etc.
1935 J. Warburg Hell Bent for Election 72 He [sc. F. D. Roosevelt] thought he was being ‘clever’ when he tried to steal Huey Long’s thunder by suddenly coming out with his ‘soak the rich’ tax message.
1935 H. L. Ickes in Lit. Digest 14 Dec. 6/3 Soak the Rich (Antonym, Soak the Poor)—Newspaperese for a system of taxation founded upon the absurd and revolutionary theory that a man should be assessed taxes in proportion to his ability to pay.
1949 A. Christie Crooked House i. 8 No Soak-the-rich taxes would have any effect on him. He’d just soak the soakers.
1959 Economist 7 Feb. 498/1 The Democratic cry that this is a ‘soak-the-poor’ Budget.
1970 Wall St. Jrnl. 29 Apr. 1/5 Soak-the-sinner tax policy remains a stand-by.‥ Taxes on alcoholic beverages and on cigarets have been the most frequent targets for increases.
1972 Listener 28 Dec. 898/3 Advocates of populist soak-the-rich policies.

He graduated from Phillips Exeter Academy in 1887 and Dartmouth College with the class of 1890.

Moses was appointed the United States Minister to Greece from 1909-1912. He was elected as a United States Senator from New Hampshire from 1918 to 1933 and served as President pro tempore of the Senate from 1925 to 1933.

URGES THE SUBSTITUTION OF
THE SMOOT MANUFACTURERS’
SALES TAX
Washington, D. C., Oct. 19.—Urging the adoption of the Smoot manufacturers’ sales tax, Senator Moses, republican of New Hampshire, told the senate today that it “would strike down the vicious system of graduated taxation which appears in the pending tax bill and which is a modern legislative adoption of the communistic dostrines of Karl Marx.”

Senator Moses, a leader in the group of eastern senators opposing the republican compromise tax revision program, declared that the finance committee measure “has been plainly drawn under the inspiration of the inspiring slogan ‘soak the rich.’”

Google News Archive
20 October 1921, Palm Beach (FL) Post, “Minority Chief Sees Tax Bill As ‘Worst Ever’” (By Associated Press), pg. 1, col. 5:
Washington, Oct. 19.—The compromise tax revision bill was assailted today in the senate by both Democrats and Republicans. Senator Underwood of Alabama, the Democratic leader, characterized the measure as the worst ever presented to congress. No one understood it, he declared, except a few treasury experts who drew it and he predicted that if the bill became law the courts would be several years interpreting it.
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Endorsing the Smoot manufacturers’ sales tax, Senator Moses declared the bill plainly was drawn under the inspiration of the slogan “Soak the rich.”

Google News Archive
6 May 1924, Providence (RI) News, “Mellon Tax Plan Dead,” pg. 8, col. 2:
Taken in all its phases the Democratic proposal has avoided the cry of “soak the rich;” it has avoided the policy of predatory wealth of “soak the poor;” it “soaks” nobody; it adopts what is good in the Mellon plan; it improves what is defective and rejects what is unsound.

11 September 1931, New York (NY) Times, “Proposals Stir Capital,” pg. 15:
“The ‘soak the rich’ idea is popular, but, of course, there is a point at which it defeats itself,” Senator Reed went on.

11 October 1931, New York (NY) Times, “Taxing the Rich,” pg. E1:
Those members of Congress who think it will be sufficient to “soak the rich” have not studied the figures.

OCLC WorldCat recordWe may soak the rich, but can we help the poor? : paper presented at the Workshop on “Income Distribution and its Role in Development”, morning session, April 26, 1974
Author: Marian Krzyzaniak
Publisher: Houston : William Marsh Rice Univ., 1974.
Edition/Format: Book : Conference publication : English

Wall Street Journal
OPINION
MAY 18, 2009
Soak the Rich, Lose the Rich
Americans know how to use the moving van to escape high taxes.
By ARTHUR LAFFER and STEPHEN MOORE
With states facing nearly $100 billion in combined budget deficits this year, we’re seeing more governors than ever proposing the Barack Obama solution to balancing the budget: Soak the rich. Lawmakers in California, Connecticut, Delaware, Illinois, Minnesota, New Jersey, New York and Oregon want to raise income tax rates on the top 1% or 2% or 5% of their citizens. New Illinois Gov. Patrick Quinn wants a 50% increase in the income tax rate on the wealthy because this is the “fair” way to close his state’s gaping deficit.